Increasing folliage/flowers on herbs such as basil, salvia, tagetes...

Hello,

I am starting to grow quite a lot of herbs, but as my space is limited, and the growing season is not 12 months long, I want to encourage my herbs (aromatics, medicinal) to produce as much leaves as possible.

With lemon balm, I just take the bigger leaves, leaving the stem, so that the tiny inter-leaves can grow and can be harvested later.

For basil, it's like a hydra: you cut one head, two pops out.

With calendula, cutting flowers seem to encourage them producing more and more flowers.

Are there any technique to increase foliage density and flower production on other plans, such as lovage, camomille, tagetes... ?

Thanks.

I'd suggest adding more nitrogen to your soil. Nitrogen is a big contributor to leaf growth.
A good way to do this at not cost is to let the rain water your plants as much as possible. When raindrops fall to the earth, they pick up nitrogen from the atmosphere and deposit it into the soil.